Brush electrode and method for ablation

Abstract

A brush electrode and a method for using the brush electrode for tissue ablation are disclosed. The brush electrode comprises a plurality of flexible filaments or bristles for applying ablative energy (e.g., RF energy) to target tissue during the formation of spot or continuous linear lesions. Interstitial spaces are defined among the filaments of the brush electrode, and the interstitial spaces are adapted to direct conductive or nonconductive fluid, when present, toward the distal ends of the brush filaments. The brush electrode facilitates electrode-tissue contact in target tissue having flat or contoured surfaces. The flexible filaments may be selectively trimmed to give a desired tip configuration or a desired standoff distance between the tissue and the conductive filaments in the brush electrode. Also, the filaments may be grouped into clusters. A shielded-tip brush electrode, including a flexible boot, is also disclosed.

1. A catheter, the catheter comprising
 an outer sheath having a distal end; 
 an inner sheath having a distal end; 
 an annular channel defined between said outer sheath and said inner sheath, wherein said annular channel is adapted to carry fluid; 
 a mechanical interface supported at least in part by said distal end of said inner sheath; 
 a flexible electrode adapted to apply ablative energy to target tissue, wherein said flexible electrode is supported by said mechanical interface, wherein said flexible electrode comprises an embedded portion and an exposed portion, and wherein said exposed portion extends from said distal end of said outer sheath and comprises a working surface; 
 a primary conductor adapted to carry ablative energy from an energy source to said flexible electrode, wherein said primary conductor comprises an uninsulated portion in electrical contact with said flexible electrode; and 
 a flexible boot at said distal end of said outer sheath, said flexible boot defining an annular fluid jacket around a booted portion of said flexible electrode, wherein said booted portion comprises at least a portion of said exposed portion of said flexible electrode, and wherein said annular fluid jacket is adapted to carry fluid that is in fluid communication with said annular channel, and said booted portion directly contacting the flexible electrode to direct the fluid to the flexible electrode. 
 
   
   
     2. The catheter of  claim 1 , wherein said inner sheath further comprises a lumen adapted to carry fluid, and wherein said mechanical interface is porous. 
   
   
     3. The catheter of  claim 1 , wherein said flexible electrode comprises a plurality of filaments defining a brush electrode having interstitial gaps between said filaments, wherein said interstitial gaps are adapted to direct fluid toward said working surface. 
   
   
     4. The catheter of  claim 3 , wherein said brush electrodes comprises a conductive core. 
   
   
     5. The catheter of  claim 4 , wherein said conductive core is circumscribed by nonconductive filaments. 
   
   
     6. The catheter of  claim 3 , wherein said brush electrodes comprises a nonconductive core. 
   
   
     7. The catheter of  claim 6 , wherein said nonconductive core is circumscribed by conductive filaments. 
   
   
     8. The catheter of  claim 1 , wherein said flexible boot is porous. 
   
   
     9. The catheter of  claim 1 , wherein said uninsulated portion of said primary conductor is looped around said booted portion of said flexible electrode. 
   
   
     10. The catheter of  claim 1 , wherein said uninsulated portion of said primary conductor is looped around a portion of said conforming electrode that is present in at least one of said annular channel and said annular fluid jacket. 
   
   
     11. The catheter of  claim 1 , wherein said outer sheath circumscribes said inner sheath, forming said annular channel between said inner sheath and said outer sheath, and wherein said annular channel is adapted to introduce fluid to said booted portion of said flexible electrode. 
   
   
     12. The catheter of  claim 1 , wherein said catheter further comprises a smooth outer wall covering said outer sheath. 
   
   
     13. The catheter of  claim 1  further comprising an annular layer of porous material within said annular fluid jacket. 
   
   
     14. The catheter of  claim 1 , wherein said brush electrodes comprises conductive filaments interspersed among nonconductive filaments, the non-conductive filaments having a greater length than the conductive filaments. 
   
   
     15. The catheter of  claim 14 , wherein said conductive filaments are grouped in clusters. 
   
   
     16. The catheter of  claim 1 , wherein said flexible electrode comprises a plurality of individual hollow filaments. 
   
   
     17. The catheter of  claim 16 , wherein said plurality of individual hollow filaments comprises at least one shortened hollow filament that extends part way into said flexible electrode, and wherein said at least one shortened hollow filaments is thereby adapted to deliver fluid to an interior region of said flexible electrode. 
   
   
     18. The catheter of  claim 1 , wherein said flexible electrode comprises a plurality of individual porous filaments.